Clinch fastener

ABSTRACT

A self-clinching fastener for insertion into ductile sheets of varying thicknesses has increased push-out and torque-out resistance. The self-clinching fastener includes a plurality of radial projections and spline teeth that embed into the ductile sheets, causing the material to cold flow into a recess, thereby permanently clinching the self-clinching fastener to the ductile sheet.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 13/669,568,filed on Nov. 6, 2012, now U.S. Pat. No. ______ issued on ______, whichis based on and claims priority to U.S. Provisional Patent ApplicationNo. 61/628,777 filed on Nov. 7, 2011, both of which are incorporatedherein by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to the field of self-clinchingfasteners. More particularly, the present invention relates to aself-clinching fastener for connection to a substrate or into an openingin a ductile material.

BACKGROUND

In the field of self-clinching fasteners, there is a need to designfasteners that have improved torque-out (rotational) and push-outresistance. Self-clinching fasteners are generally well-known in the artand have many different designs. Self-clinching fasteners attach tometal sheets, substrates, or openings in ductile material withoutwelding or additional fasteners. When typical self-clinching fastenersare pressed into pre-punched, drilled, or reamed holes in ductile metal,the ductile metal cold flows into recesses and features of theself-clinching fastener to secure it to the metal. The recesses andfeatures of existing self-clinching fasteners take a variety of forms,including knurls, ribs, and serrated clinching rings to name a few.Typical self-clinching fasteners utilize tooling in the die to locallycompress the ductile metal into a recess on the fastener to secure it tothe ductile metal. Once a self-clinching fastener is inserted into theductile metal, the self-clinching fastener is permanently attached tothe metal, and removal of the fastener results in either failure of themetal or the fastener.

Existing self-clinching fasteners suffer from a number of shortcomingssuch as limited torque-out resistance and limitations regarding thethickness of metal and shape of the hole into which the self-clinchingfastener may be secured. Typical self-clinching fasteners require verytight tolerances in both the fastener itself and the hole into which thefastener is being installed. In particular, tight tolerances exist forboth the size of the hole and the thickness of the sheet. The reason fortight hole size and sheet thickness tolerances is two-fold. First,existing self-clinching fasteners include features that prevent rotationof the fastener. Such features provide recesses or pockets into whichthe ductile metal cold flows during installation. Examples of thefeatures are serrated rings, knurled studs, ribs, or a hexagonal shapedhead that embeds into the surface of the metal. Second, there must beenough material immediately around the hole to cold flow into thevarious recesses and features of the self-clinching fastener to securethe fastener to the sheet and provide adequate push-out resistance. Forexample, if a self-clinching fastener is pressed into a hole that isslightly too large for the fastener, there may be insufficient materialto flow into the recesses and features of the fastener thereby causingthe connection between the fastener and the metal sheet to be weakerthan anticipated and the fastener may fail during normal use.

Additionally, as sheet thickness increases, existing self-clinchingfasteners sometimes require additional machining such as drilling and/orcounter-boring of the ductile metal combined with special die tooling toadequately compress the ductile metal into the recesses of theself-clinching fastener to securely clinch the fastener. Such additionalmachining and special die tooling are often prohibitively expensive.Self-clinching fasteners for thick materials typically use knurledshoulder sections to resist torque-out. However knurls have shallowtooth depth, making them ill-suited for rough punched holes. The innerdiameters of rough punched holes are tapered due to the punch processcausing loss of engagement with the knurls. Subsequent hole reaming isoften needed to prevent torque-out of such knurled-shoulderself-clinching fasteners.

Thus, there is a need for a self-clinching fastener that has highresistance to torque-out and push-out, can be attached to material ofvarying thickness, and can be attached to holes that do not have specialgeometry or pre-formed, or post-machined surfaces.

SUMMARY

The present invention relates to a self clinching fastener forconnection to ductile material. One embodiment of the self-clinchingfastener includes a head with an inner surface and an outer surface, theinner surface including a plurality of radial projections extendingtherefrom and positioned around the central axis of the self-clinchingfastener. An anti-rotation protrusion is adjacent to and projecting fromthe inner surface of the head further includes a plurality of splineteeth extending radially from the central axis of the anti-rotationprotrusion. The self-clinching fastener further includes a clinchedmaterial recess adjacent to the anti-rotation protrusion for acceptingclinched material that is displaced by the plurality of spline teethwhen the self-clinching fastener is pressed into the ductile material.It should be understood that similar design features could be used todesign a staked nut, standoff, or other feature without departing fromthe invention.

It will be understood by those skilled in the art that one or moreaspects of this invention can meet certain objectives, while one or moreother aspects can lead to certain other objectives. Other objects,features, benefits and advantages of the present invention will beapparent in this summary and descriptions of the disclosed embodiment,and will be readily apparent to those skilled in the art. Such objects,features, benefits and advantages will be apparent from the above astaken in conjunction with the accompanying figures and all reasonableinferences to be drawn therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a self-clinchingfastener in accordance with the invention, shown with the punch and dieused to attach the fastener to a ductile sheet.

FIG. 2 is another perspective view of the self-clinching fastener ofFIG. 1.

FIG. 3 is a side view of the self-clinching fastener of FIG. 1.

FIG. 4 is a bottom view of the self-clinching fastener of FIG. 1.

FIG. 5 is a side view of the self-clinching fastener of FIG. 1, shownimmediately before being clinched to a ductile sheet, the ductile sheetand die shown in cross-section.

FIG. 6 is a side view of the self-clinching fastener of FIG. 1, shown asit is being clinched to a ductile sheet, the ductile sheet and die shownin cross-section.

FIG. 7 is a side view of the self-clinching fastener of FIG. 1, shownclinched to a ductile sheet, the ductile sheet and die shown incross-section.

FIG. 8 is a detail view of the self-clinching fastener of FIG. 7 takengenerally along the line 8-8 in FIG. 7, with the ductile sheet and dieshown in cross-section.

FIG. 9 is a bottom perspective view of the self-clinching fastener ofFIG. 1 with the self-clinching fastener clinched to the ductile sheet.

FIG. 10 is a side view of the self-clinching fastener of FIG. 1 with theself-clinching fastener clinched to the ductile sheet.

FIG. 11 is a detail view of the self-clinching fastener of FIG. 9 takengenerally along the line 11-11 in FIG. 9.

FIG. 12 is a top view of the self-clinching fastener of FIG. 1 with thefastener clinched to the ductile sheet.

FIG. 13 is a perspective view of another embodiment of a self-clinchingfastener in accordance with the invention.

FIG. 14 is a section view of the self-clinching fastener of FIG. 13shown clinched to a ductile sheet with the punch and die.

FIG. 15 is a perspective view of another embodiment of a self-clinchingfastener in accordance with the invention.

FIGS. 16-18 are perspective views of a thick ductile sheet showing theeffect of the self-clinching fastener of FIG. 1 on the sheet as it isinserted into the sheet.

FIG. 19 is a section view of the self-clinching fastener, ductile sheet,and die of FIG. 1.

FIG. 20 is a perspective view of the self-clinching fastener, ductilesheet, and die of FIG. 1 shown with the self-clinching fastener clinchedto the ductile sheet, the ductile sheet and die shown in cross-section.

FIG. 21 is an exploded view of the self-clinching fastener, ductilesheet, and die of FIG. 1.

FIG. 22-23 are perspective views of a thin ductile sheet showing theeffect of the self-clinching fastener of FIG. 1 on the sheet as it isinserted into the sheet.

FIG. 24 is a section view of another embodiment of a self-clinchingfastener in accordance with the invention shown clinched to a ductilesheet and shown in section.

FIG. 25 is a section view of the self clinching fastener of FIG. 1 shownclinched to a ductile sheet also shown in section.

DETAILED DESCRIPTION

Referring to FIG. 1, one embodiment of a self-clinching fastener 100 inaccordance with the invention is shown. In the embodiment shown, theself clinching fastener 100 is permanently attached to a nominal metalsheet 200 by inserting the self clinching fastener through a hole 210and pressing it into place using a punch 300 and die 400 to press theself-clinching fastener onto the metal sheet. The nominal metal sheethas a punch side 220 and a die side 230. Although the embodiment shownshows the self-clinching fastener 100 clinched to a nominal metal sheet200, the self-clinching fastener may be clinched to any ductile materialwithout departing from the invention.

Turning now to FIGS. 2-4, the self-clinching fastener 100 is shown ingreater detail. In the embodiment shown, the self-clinching fastener 100includes a head portion 102, a threaded portion 104 having a smallerouter diameter than the head portion and extending from the sheet-sideface 106 of the head portion. Of course, self-clinching fasteners mayinclude different fastening means extending from the head portionwithout departing from the invention. For example, self-clinchingfasteners in accordance with the present invention may also include butare not limited to spacers, standoffs, floating nuts, threaded accesshardware, locking fasteners, non-threaded fasteners, concealed head,blind, or sheet joining fasteners. A plurality of radial projections 108are formed onto the sheet-side face 106. In the embodiment shown, theradial projections 108 are semi-circular, but other shapes may be usedwithout departing from the invention. FIGS. 13 and 15 showrepresentative examples of alternative shapes.

Adjacent to and extending from the sheet-side face 106 is ananti-rotation protrusion 103 that includes a plurality of spline teeth110 extending radially from the central axis of the self-clinchingfastener 100 and a recess 112 with a diameter less than the outerdiameter of the threaded portion 104. In the embodiment shown, theplurality of spline teeth 110 extend away from the sheet-side face 106 amajority of the thickness of the nominal metal sheet 200, but extendless than the total thickness of the metal sheet. Each tooth 110includes a shoulder 111 that helps push clinched material 212 (see FIGS.6-8) into the recess 112.

The recess 112 provides an area into which clinch material 212 (SeeFIGS. 6-8) from the nominal metal sheet 200 flows when the selfclinching fastener 100 is pressed into the metal sheet. The clinchmaterial 212 that flows into the recess 112 is captured, therebyclinching the self-clinching fastener 100 to the nominal metal sheet200. In the self-clinching fastener 160 shown in FIGS. 13-14, an annularring 162 is included, which provides a continuous surface for the clinchmaterial 212 to flow against, thereby containing it in the recess 112.Although not required, including an annular ring 162 increases push-outresistance over self-clinching fasteners that rely on the threads tocontain the flow of the clinch material 212 in the recess 112.

In the embodiment shown in FIGS. 1-14, there are eight spline teeth 110and eight radial projections 108, but more of less of each may be usedwithout departing from the invention. Additionally, the orientation ofthe plurality of spline teeth 110 and plurality of radial projections isoffset in the embodiment shown, but other orientations may be usedwithout departing from the invention. The plurality of radialprojections 108 and spline teeth 110 provide torque-out resistance sothat when the self-clinching fastener 100 is attached to the nominalmetal sheet 200 it does not rotate in the hole. The plurality of splineteeth 110 also pushes clinch material 212 into the recess 112 as theself clinching fastener 100 is pressed into the nominal metal sheet 200.

Turning now to FIGS. 5-12, the insertion of the self-clinching fastener100 into the nominal metal sheet 200 is shown. FIG. 5 shows theself-clinching fastener 100 just prior to insertion into the nominalmetal sheet 200. A punch 300 and die 400 are used to press theself-clinching fastener 100 into the nominal metal sheet 200. FIG. 4shows the self-clinching fastener 100 partially inserted into thenominal metal sheet 200. During insertion, the plurality of spline teeth110 displaces clinch material 212 from area surrounding the hole 210causing the clinch material to flow into the recess 112 of theself-clinching fastener 100. The plurality of spline teeth 110 onlydisplace clinch material 212 in their path, thereby creatingcorresponding pockets in the metal sheet which further secure theself-clinching fastener 100 and increase the torque-out resistance ofthe self-clinching fastener. Including spline teeth 112 rather thanknurls allows deeper pockets to be formed into the nominal metal sheet200.

FIGS. 7-12 show the self-clinching fastener 100 fully installed in thenominal metal sheet 200. The clinch material 212 displaced by theinsertion of the self-clinching fastener 100 takes a shape defined bythe die 400 and features of the self-clinching fastener 100 including,but not limited to the recess 112 and the plurality of spline teeth 110.In the embodiment shown, the clinch material 212 is not displaced as acontinuous piece, but has gaps or seams 213 depending on a number offactors including, but not limited to the diameter of the hole 210, thethickness of the nominal metal sheet 200, and the diameter of the die400. The die 400 may also have a small chamfer or lead-in radius butgenerally, the die has an inner diameter slightly larger than the majordiameter of the threaded portion 104. Using a die 400 with a slightlylarger diameter than the major diameter of the threaded portion 104minimizes the size of the clinch material 212. The clinch material 212clinches the self-clinching fastener 100 to the nominal metal sheet 200and resists push-out while also providing a confined and undistortedregion around the clinched surface. Unlike prior art self-clinchingfasteners that have significant protrusions or recesses in the clincharea that interfere with sealing or being able to attach a nut to theexposed surface of the nominal metal sheet 200, the present inventionallows for fasteners that leave the punch-side surface 220 of the metalsheet undisturbed. This is especially useful in instances where gasketsor other seals are attached to the nominal metal sheet 200 by theself-clinching fastener because a more complete and effective seal canbe created.

The plurality of spline teeth 110 and the plurality of radialprojections 108 both independently and together provide resistance torotation. The plurality of spline teeth 110 engage the inner diameter ofthe hole 210 and the thickness of the nominal metal sheet 200. Theplurality of radial projections 108 are embedded into the nominal metalsheet 200 when the self-clinching fastener 100 is clinched to the sheet.Although the embodiment shown includes both spline teeth 110 and radialprojections 108 on the same fastener, the spline teeth 110 greatlyimprove torque-out and push out resistance independent of the radialprojections 108, and a fastener including only the spline teeth 110 andlacking the radial projections 108 does not depart from the invention.

Turning now to FIG. 14-16, the effect of the self-clinching fastener ona ductile sheet 500 is shown. The ductile sheet 500 has a die side 510and a punch side (not shown). FIG. 14 shows a pre-punched or drilledhole 520 in the ductile sheet 500. FIG. 15 shows the ductile sheet 500after partial insertion of the self-clinching fastener 100 (not shown).As previously discussed, the plurality of spline teeth 110 pushes clinchmaterial 512 in the direction of insertion of the self-clinchingfastener 100. As the clinch material 512 is pushed, it cold flowsinward, reducing the diameter of the hole 510, and filling the recess112, thereby clinching the fastener to the ductile sheet 500. Of course,as the self-clinching fastener 100 is inserted farther into the ductilesheet 500, the plurality of spline teeth 110 pushes more clinch material512 into the recess 112. FIG. 16 shows the profile of the hole 510 afterthe self-clinching fastener 100 has been fully seated into the ductilesheet 500. When the plurality of radial projections 108 are pressed intothe surface of the ductile sheet 500, it forms anti-rotation lobes 514into the ductile sheet.

Alternatively, the self-clinching fastener 300 may be secured to metalsheets of greater or lesser thickness than the nominal metal sheet 200shown in FIGS. 5-12. FIGS. 5-12 and 17-23 show the effect of insertingthe self-clinching fastener 100 into metal sheets of varying thickness.For purposes of the following, metal sheets are categorized into threecategories based on the ratio of sheet thickness to the length of theplurality of spline teeth 110: (1) a thick metal sheet 600 has athickness greater than the axial length of the plurality of spline teeth110 (see FIG. 23), (2) the nominal metal sheet 200 has a thicknessapproximately the same as the axial length of the plurality of splineteeth 110 (see FIGS. 5-12), and (3) a thin metal sheet 700 has athickness less than the axial length of the plurality of spline teeth110 (see FIGS. 17-21).

FIG. 23 shows the insertion of the self-clinching fastener 100 into athick metal sheet 600. Clinching the self-clinching fastener 100 to thethick metal sheet 600 causes shoulders 111 on the plurality of splineteeth 110 to force clinch material 612 into the recess 112. A die (notshown) supports the metal sheet, but the hole 610 confines the clinchmaterial 612 such that it is forced into the recess 112. If the thickmetal sheet 600 is sufficiently rigid, it would be possible to clinchthe self-clinching fastener 100 to the thick metal sheet 600 withoutusing a die.

FIGS. 5-12 shows the insertion of the self-clinching fastener 100 to anominal metal sheet 200. Clinching the self-clinching fastener 100 to anominal metal sheet 200 causes the shoulders 111 to push clinch material212 into the recess 112. As shown in FIGS. 7 and 8, the die 400 helpsguide the clinch material 212 into the recess.

FIGS. 17-21 show the insertion of the self-clinching fastener 100 to athin metal sheet 700. The thin metal sheet has a die side 720 and apunch side 730. Clinching the self-clinching fastener 100 to a thinmetal sheet 700 causes the die 400 to confine the clinch material 712pushed by the plurality of spline teeth 110 between the die and theself-clinching fastener. Additionally, the die 400 peens or flares theends 116 of the plurality of spline teeth 110 back against the die side720 of the thin metal sheet 700. In the embodiment shown, the pluralityof spline teeth 110 are offset from the radial projections 108, whichcauses the thin metal sheet 700 to be clinched into a wave pattern,which increases both push-out and torque-out resistance. Of course, theplurality of spline teeth 110 and radial projections 108 may havealternate orientations to each other without departing from theinvention.

Turning now to FIGS. 13 and 22, alternative embodiments ofself-clinching fasteners are shown. FIG. 13 shows a threaded stud 150with radial projections 152 in an alternative configuration. Of course,the profile of the plurality of spline teeth 154 and the radialprojections 152 may vary without departing from the invention. Here, theradial projections 152 have profiles similar to the plurality of splineteeth 154, with pockets 156 between the radial projections for materialdisplaced by the radial projections to flow into. FIG. 24 shows aself-clinching nut 170 with the same clinching features asself-clinching fastener 100.

Although the invention has been herein described in what is perceived tobe the most practical and preferred embodiments, it is to be understoodthat the invention is not intended to be limited to the specificembodiments set forth above. Rather, it is recognized that modificationsmay be made by one of skill in the art of the invention withoutdeparting from the spirit or intent of the invention and, therefore, theinvention is to be taken as including all reasonable equivalents to thesubject matter of the appended claims and the description of theinvention herein.

What is claimed is:
 1. A self-clinching fastener for connection to ahole in ductile material and including a central axis, theself-clinching fastener comprising: a head including an inner surfaceand an outer surface; an anti-rotation protrusion adjacent to andprojecting from the inner surface of the head and including a pluralityof teeth extending radially from the central axis; a clinched materialrecess adjacent to the anti-rotation protrusion; and each of theplurality of teeth having shoulder portions that cause the ductilematerial to flow into the clinched material recess when theself-clinching fastener is pressed into the ductile material.
 2. Theself-clinching fastener of claim 1, wherein the self-clinching fasteneris pressed into the hole in the ductile material with a punch and die.3. The self-clinching fastener of claim 1, wherein the plurality ofteeth are offset from a plurality of projections extending radially fromthe inner surface around the central axis.
 4. The self-clinchingfastener of claim 1, further including an annular portion adjacent tothe clinched material recess.
 5. The self-clinching fastener of claim 4,further including a threaded portion adjacent to and projecting from theannular portion.
 6. The self-clinching fastener of claim 1, furtherincluding a threaded portion adjacent to and projecting from theclinched material recess.
 7. The self-clinching fastener of claim 1,wherein the self-clinching fastener is a nut.
 8. The self-clinchingfastener of claim 1, wherein the self-clinching fastener is a standoff9. The self-clinching fastener of claim 1, wherein the self-clinchingfastener is a non-threaded fastener.
 10. The self-clinching fastener ofclaim 1, wherein the self-clinching fastener is a blind fastener.